Search form

Electric Bus, Where Art Thou?

Amid the stimulus-backed hullabaloo over high speed rail, perhaps efforts by municipalities to supplant old-school diesel with new era electric bus fleets have been overshadowed. Maybe it is still too soon, but there has been little media coverage on cities making the switch from diesel to hybrid or electric buses; however, with the money that is being pumped in, and the major shift in national perspective on the importance of sustainability, energy efficiency, and pollution reduction, now is the time to bypass the delays of a hybrid "stepping stone" and leap straight for all-electric transit systems.

There is a great passage in the science fiction story Earth by David Brin where he suggests that the American space shuttle was the most complicated machine ever built. From that point forward, he writes, engineers employed technology and software to minimize the number of parts, and therefore, the complexity of mechanical systems. Reduced number of parts allows for fewer raw materials, lower weight and hence lower power requirements. Most importantly, fewer parts results in increased reliability as the number of ways a system can fail (mechanically) decreases proportionally. You can already see this phenomenon in what is popularly referred to as "convergence", that is, multiple devices (i.e. cameras, mp3 players, cell phones, game players, etc.) converging into a single device that uses software to capitalize on common hardware components shared by several systems.

All this talk about "number of parts" is a lead-in to the idea that hybrid-electric technology is not, by any means, a categorical solution to the woes of internal combustion; rather, it is merely a "stepping stone" to get us from 100% fossil fuel to 100% electric locomotion. Between these two states, so-called hybrid vehicles are a combination of two parallel locomotion systems used to glean the air quality and energy efficiency benefits of all-electric systems while compensating for the limitations of current battery technology on range and support of onboard systems, such as climate control, with assistance from a smaller internal combustion engine. But with the need for two systems, hybrid vehicles increase in complexity, number of parts, and therefore, potential for failure (it's kind of like the even-bigger mess one must make in the process of cleaning one's room). Moreover, raw material requirements, emissions, reliance on fossil fuel, and noise associated with internal combustion are all present (albeit reduced) with hybrid vehicles. Indeed, it would be interesting to compare the carbon footprint on a hybrid vehicle to that of a standard fossil fuel vehicle for these reasons (but please let's not waste our time there!).

For personal cars, cutting edge all-electric technology is only now reaching acceptable range/charge-time stats. This is not so for buses, however. Many cities, such as Chattanooga, Santa Barbara, and Miami Beach, have been successfully operating all-electric bus systems for over ten years. Electric vehicle enthusiasts will passionately reaffirm the fact that electric bus systems operated just fine, even in large municipalities such as New York City, until the "limitless supply" of cheap fossil fuels in the early 20th Century made the internal combustion engine more attractive (and don't forget about the "Great American Streetcar Scandal"). When it comes to municipal bus fleets, particularly in smaller cities with shorter routes and lower ridership, the use of hybrid instead of all-electric bus technology is more than a bit puzzling. Existing all-electric bus system precedents and all the faults of hybrid systems listed above point to the conclusion that, in many cases, we are simply not using the right tool for the job.

In years past, an unmotivated (read: no cost incentive) move away from fossil fuels barely justified the gradual adaptation from internal combustion to all-electric in the form of a hybrid "stepping stone" technology across the spectrum of transport systems. But now that the spectre of soaring fuel costs are hurtling us towards sustainability in high gear, the need for this stepping stone is not universal and, in some cases, counter-effective. For municipal transit systems at least, a more careful implementation of the most appropriate technology will allow us to move faster towards sustainability and simpler, more efficient transit vehicles. The sooner we employ all-electric technology in applicable transit systems the sooner hybrid buses will seem as convoluted as the space shuttle.

Ian Sacs, P.E. is a worldwide transportation solutions consultant based in Finland.

Trackless Trolleys

I agree. I've been wondering lately what the cost trade-off is between creating and maintaining a trackless trolley system like the one's I'm familiar with in Cambridge, MA vs. buying and maintaining hybrid or electric buses. Besides the obvious issues of the up-front cost of constructing an overhead catenary system and purchasing an entire fleet of new trackless trolleys vs. incrementally replacing older buses with hybrid or electric ones, of course.

I know that Maryland is buying 100 new hybrid buses for $62 million ($620,000 per bus), which is about a $120K to $170K premium per bus, or up to a $17 million premium for hybrids. Could one or more routes have been wired with catenaries and those buses been replaced with trackless trolleys for the same amount? Would there have been an equivalent reduction in pollution? How would maintinence compare between the two systems? Or between catenary maintinence and battery maintinence/replacement on all-electric buses?

Having seen the effect that a fixed transit infrastructure like streetcars can have on development and local investment, I also wonder if trackless trolleys have a similar impact on their surroundings due to the static nature of their infrastructure.

It may be worth talking to

It may be worth talking to Seattle, San Francisco, etc. and getting figures for maintaining trolleybuses and wires. My guess is that it's more cost effective for larger systems than for smaller ones.

Whether trolleybuses are as effective as fixed rail in encouraging development is an open question, especially in areas that have no real tradition of operating them. A new setup would also have to deal with opposition against the wires (that is part of what sunk LA's proposed trolleybus network in the 1990's--they eventually settled on CNG instead).

As much as I'd like to see streetcar lines which have a longer life-span (IIRC) come first, there is certainly a role for buses to complement them and one big issue is all that nasty gas they belch out. I always stay well behind local COTA buses. Granted, they're improving service, routes, will be adding articulated buses, and have seen a large increase in the percentage of riders. A big plus is that they all come equipped with a bike rack on the front. Hopefully, as things continue to improve for COTA (whose image has long been unfavorable) financially they will be able to consider adding electric buses.